The processes of non-catalytically cracking and catalytically cracking hydrocarbon feedstocks are well known in the art. In this regard, steam cracking in a furnace and contact with hot non-catalytic particulate solids are two well-known examples of non-catalytic cracking process. Examples of non-catalytic cracking processes of these types are disclosed in, for example, Hallee et al., U.S. Pat. No. 3,407,789; Woebcke, U.S. Pat. No. 3,820,955; DiNicolantonio, U.S. Pat. No. 4,499,055 and Gartside et al., U.S. Pat. No. 4,814,067.
Additionally, catalytic cracking processes are known. For example, fluid catalytic cracking processes have been described in the patent literature in Cormier, Jr. et al., U.S. Pat. No. 4,828,679; Rabo et al., U.S. Pat. No. 3,647,682; Rosinski et al., U.S. Pat. No. 3,758,403; Lomas, U.S. Pat. No. 6,010,618; and Gartside et al., U.S. Pat. No. 5,324,484. Special mention is made of the improvements in fluid catalytic cracking described in Letzsch et al., U.S. Pat. No. 5,662,868 and Letzsch et al., U.S. Pat. No. 5,723,040.
Another catalytic cracking process that is especially useful in producing olefins from hydrocarbon feedstocks has been termed the deep catalytic cracking processes. The deep catalytic cracking process is described in Li et al., U.S. Pat. No. 4,980,053; Yongqing et al., U.S. Pat. No. 5,326,465; Shu et al., U.S. Pat. No. 5,232,675; Zhicheng et al., U.S. Pat. No. 5,380,690 and Zaiting et al., U.S. Pat. No. 5,670,037.
The olefins produced in these processes have long been desired as feedstocks for the petrochemical industries. Olefins such as ethylene, propylene, the butenes and the pentenes are useful in preparing a wide variety of end products, including but not limited to polyethylenes, polypropylenes, polyisobutylene and other polymers, alcohols, vinyl chloride monomer, acrylonitrile, methyl tertiary butyl ether and other petrochemicals, and a variety of rubbers such as butyl rubber. Additionally, the heavier hydrocarbons produced in the processes have also been long desired for use as gasolines, fuels and light cycle oils.
It would constitute a significant advancement in the state of the art if an improved deep catalytic cracking process could be developed which could handle a wide variety of feedstocks and crack these feedstocks to more valuable olefins (C3 and C4 olefins) with less C2 olefins. It would represent a further significant advancement in the state of the art if the improved process could be readily and easily applied to revamping an existing catalytic cracking process.